Actually, it doesn't always. As long as the relationship is unique, the cross-reference itself can be treated as a multi-column primary key, even if it isn't defined as such in the database.

Can you give an example? I'm still learning about Class::DBI, but thus far I have not found a way to avoid it claiming the first column as a primary key (in the absence of such a declaration in the DB table itself).

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other